Problem: $ {-3\cdot \left[ \begin{array}{cc} 3 & -1 & 1 \\ -1 & 2 & 1 \end{array} \right]=}$
Solution: The Strategy To multiply a matrix by a scalar, we multiply each term of the matrix by the scalar. Multiplying each term $ {\begin{aligned}-3\cdot \left[\begin{array}{rr} {3} & {-1} & {1} \\ {-1} & {2} & {1} \end{array}\right]&=\left[\begin{array}{rr} -3\cdot{3} & -3\cdot{-1} & -3\cdot{1} \\ -3\cdot{-1} & -3\cdot{2} & -3\cdot{1} \end{array}\right] \\\\&=\left[\begin{array}{rr} {-9} & {3} & {-3} \\ {3} & {-6} & {-3} \end{array}\right]\end{aligned}}$ Summary $ {-3\cdot \left[ \begin{array}{cc} 3 & -1 & 1 \\ -1 & 2 & 1 \end{array} \right]=\left[ \begin{array}{cc} -9 & 3 & -3\\ 3 & -6 & -3 \end{array} \right]}$